The present invention relates to a drive device for four-wheel drive motor vehicles.
Four-wheel-drives for motor vehicles, in particular passenger cars, can be roughly divided into permanent drives with two axle differentials and an intermediate axle differential (for avoiding drive tensions) and so-called hang-on drives with a primary axle that is directly driven by the drive aggregate and a secondary axle that can be activated via a clutch (for example a viscous clutch or a Haldex clutch) in the case of drive slip. The primary axle or secondary axle can hereby be the front axle or the rear axle of the motor vehicle.
JP 2005 035 379 A1 discloses a drive device in which the secondary axle of the motor vehicle is driven via a toothed belt drive as transmission means form the primary axle to the secondary axle. The differentials of the two axles are arranged in a conventional manner coaxial to the drive shafts that output to the wheels. Further a controllable clutch is provided via which the force flux to the secondary axle can be interrupted for achieving for example only a front drive of the motor vehicle.
From WO 81/03150 a generic drive device is known in which a secondary axle is impinged, via two lateral belt drives, by the primary axle of the motor vehicle or drive shafts of the primary axle that output on the wheels. A differential is only provided on the primary axle, which odes not allow satisfactorily compensating differences in rational speed of the wheels in particular driving through curves.